Written by Darian Livingstone | Ceres Industries
(306) 653-7258 |
From the time of birth to the time of shipping, a calf experiences numerous stressors while on the farm that can be physiologically harmful to a calf's well-being. These stressors come in many forms: environmental, social, physiological, and nutritional. They are heightened during conventional management practices. Weaning, castrating, dehorning, and transportation, to name a few, are practices commonly done on the farm that cause a great deal of stress to the calf.
Cortisol is a hormone released as a response to stress and triggers the body's "fight-or-flight" response. Under normal circumstances, this is a healthy reaction since it triggers the body's response that corrects the situation. A classic example of this is when your body spikes cortisol levels in the morning to signify that it's time for you to eat. This helps to correct the nutritional stress occurring. However, many farm practices, such as weaning, occur over an extended time, meaning cortisol levels remain spiked longer.
Since cortisol activates the fight-or-flight response, it simultaneously slows other body functions associated with maintenance, also known as the rest-and-digest phase. Digestion and immunity are just two examples that take a major hit when stress is prolonged. The fight-or-flight response is incredibly detrimental to a calf's productivity and welfare.
Calves that are chronically stressed are extremely susceptible to immunosuppression. Cortisol causes decreased lymphocytes (white blood cells in the lymphatic system) and inhibits the inflammation response. This immune suppression increases an animal's risk of infection and illness. Combined with the fact that calves are born with 20% fewer lymphocytes, they are already immunosuppressed.
Numerous steps can be taken to help reduce the amount of anxiety a calf experiences to mitigate the adverse effects of stress and improve calves' overall welfare and health. Some of these steps include dietary or husbandry practice adjustments.
Some husbandry practices that can be adjusted to make the experience less stressful for calves are castration, dehorning, and weaning. The former two can be adjusted by administering an analgesic and anesthetic to reduce the pain (physical stress) that a calf endures. Additionally, the timing of the procedure can help, as well. Performing these when a calf is as young as possible and done apart from other on-farm practices, such as weaning, reduces anxiety and stress. Weaning is a time of anxiety (emotional stress) for calves. In conventional systems, they experience a change of environment, loss of their mother, change in diet, and exposure to unfamiliar animals. Converting to a two-stage weaning or fence-line weaning program can significantly reduce the anxiety felt by a calf (and mother).
Nutritionally speaking, steps can be taken to aid a calf through the stressful experience. Although a stressed calf's nutritional requirements are no higher than a calm calf, their intake decreases significantly, which means they are taking in fewer nutrients. So now, stress has compromised the immune system by eliciting the release of cortisol, and calves aren't being supplied enough nutrients to meet the demands of the immune system. Essential trace minerals play a huge role in the immune system, so supplementation is key to a healthy calf.
Copper plays a role in certain white blood cells' functions: neutrophils, which are involved in killing pathogens. Although research reports state that supplying additional copper has no known benefits, they also state that calves with low bodily reserves are more susceptible to infections. Non-stressed calves require 10 mg/kg daily, as per the NRC, but stressed calves should receive as much as 15 mg/kg daily.
Zinc is involved in many signalling molecules and white blood cells within the immune system. Zinc is also involved in producing antibodies and initiates inflammation, which then activates other immune cells. Finally, this mineral is a component of a type of white blood cell called macrophages. These cells detect and destroy bacteria and other harmful organisms, preventing infections.
Selenium doesn't have a clear responsibility within the immune system; however, it is well known that it is important none-the-less. It is known that selenium has antioxidant properties and works closely with vitamin E to protect the body from oxidative stress.
Texas A&M Study performed by JC Branum showed that copper and zinc levels in the liver significantly decreased from birth to weaning (approx. 236 days of age). Selenium also significantly declines since milk is a poor source of trace minerals.
Free-choice supplements (ex. lick tubs, premixes) are often used to supply nutrients to calves. However, since intake decreases drastically at the time of weaning, these can have little effect. Providing free-choice supplements to calves before weaning can help them become familiar with them, and intake will take a smaller dive post-weaning.
Most supplements are formulated with mature cows in mind, but a calf's intake will be about 50% of a cow's, so they will often balance themselves. Providing Supremix® Winter to calves, before and after weaning, is an effective way to ensure that calves are receiving adequate minerals. The chelated minerals and high levels of vitamins will help ensure your calves have a strong immune system. If you require protein and energy as well, the Saltec® Fortified Pro is a great option to provide these extra nutrients.
For more information about our products, please contact Ceres Industries at (306) 653-7258.
References
Garrett, J.. 2015. Trace minerals and the cow’s immune system. Progressive Dairy. [blog] https://www.progressivedairy.com/topics/feed-nutrition/trace-minerals-and-the-cow-s-immune-system
Livingstone, D.. 2017. Reducing Stress During Pre- and Post Weaning to Improve Quality of Life and Productivity of Beef Calves. University of Saskatchewan; Agirculture and Bioresources. [thesis]
N.A. 2018. Supplementing for Calf Weaning Success. Drovers. [blog] https://www.drovers.com/article/supplementing-calf-weaning-success
Scholljegerdes, E.. 2016. Non-stressed vs stressed calves’ mineral requirements. Progressive Cattle. [blog] https://www.progressivecattle.com/topics/feed-nutrition/non-stressed-vs-stressed-calves-mineral-requirements